[FTC]: Caster?

[dradel]

Again not knowing the rules at all, but the way I see it the caster ball only has one moving part

[GeeTwo]

Originally Posted by dradel

Not familiar with ftc rules, but would this work?
http://www.mcmaster.com/#ball-casters/=10ll5k3

Originally Posted by dradel

Again not knowing the rules at all, but the way I see it the caster ball only has one moving part

A ball and socket joint, while only having one moving part, has two degrees of freedom: altitude and azimuth, or latitude and longitude.

[IndySam]

For competition robotics purposes, casters are evil and should be avoided.

[pilum40]

Indy:
sorry to be obtuse. My team is asking me why casters are evil? Again, I'm just a teacher, not an engineer. Not trying to be funny but legitimately would like to give them a reason why. It's a teachable moment for all. thanks for your patience.

[IndySam]

They are never in the position you want them to be in and can cause irregular movement.

They also violate one of the rules of competition robotics: If it touches the floor it must be powered.

[RRLedford]

Originally Posted by IndySam

They are never in the position you want them to be in and can cause irregular movement.

They also violate one of the rules of competition robotics: If it touches the floor it must be powered.

You are conflating the term "rules" With "rules of thumb" that good designers follow.
The official game rules of the Res-Q competition do not exclude the use of casters, unless perhaps they have both a swivel and a shock absorber too (2 degrees of movement freedom → rotation & elevation).

Three wheeled drives are rather tippy and unstable. Casters can typically get turned away from desired direction too often and too easily, especially if you will ever be trying to back down the mountain.
If your star wheels work well, I assume that going for the 40 points that reaching the high mountain zone would give you in autonomous would be possible, but getting back down without a rear caster becoming stuck on churros would be near impossible and risk a rollover backwards.

I am glad to hear someone has done a pair of front "star wheels" that successfully navigate the mountain & churros.

Mecanum wheels will not work very well as only a pair at rear, since they are meant to be used as a set of four located at the corners of a square.

A driven pair of of at least 4" diameter omni wheels at rear would likely work best, and give good results both on the mountain and in the floor.

-Dick Ledford